The invention relates to an adjustable electromechanical device in a housing. The device comprises a shaft which is rotatably mounted in the housing. The shaft carries one or more contact elements and is jounalled in a cylindrical bearing sleeve. Axial movement of the shaft is prevented by the cooperation of at least one projection on the bearing sleeve with a circumferential groove in the shaft.
Such a device which may be a potentiometer, a variable capacitor or a multiple switch, is described in German Patent Application No. 2,850,835 (corresponding to U.S. Pat. No. 4,296,292). In this known device, the projection is formed on the bearing sleeve by deforming the wall of the sleeve form the outside of the sleeve. Consequently, the precision with which the projection is reproduced at the inner side of the bearing sleeve is not very high. The grooved shaft must be capable of moving loosely relative to the projection, yet without too much play.
The known device is depicted in FIGS. 1 and 2 of the accompanying drawing. FIG. 1 is a partly-sectional side view and FIG. 2 is a sectional view along the line II--II of FIG. 1.
In these FIGS. 1 and 2, reference numeral 1 represents the housing of the known device and 2 a bearing sleeve in which a shaft 3 can rotate. On the inner side of the bearing sleeve 2 there is a projection 4 which is obtained by deforming the wall of the sleeve 2 from the outside of the sleeve 2. The projection 4 slides in a circumferential groove 5 in the shaft 3. A stop 6 is formed in the bottom of the groove 5 in shaft 3.
It will be clear that it is very difficult to obtain a projection 4 which fits correctly in the groove 5. Without a correct fit there is a fair chance that the projection 4 will jam in the groove 5. Obviously, this also depends on the material chosen for the bearing sleeve 2.
An interesting feature of the known version is that the projection forms an integral part of the bearing sleeve.